This invention relates to switch arrangements for both wired and wireless terminals.
Wireless telephones are becoming ubiquitous. Presently, they are used in specialized wireless networks. In the cellular network, cellular telephones communicate with base stations (which form the centers of cells) and the base stations relay the communications to the more expansive "landline" switching networks. Typically, the wireless networks are at least in part geographically co-extensive with the landline networks but other than at the interface points, they do not co-mingle.
It is desirable, of course, to create an arrangement in which the two networks are effectively merged. Viewed differently, it would be beneficial to augment some of the apparatus in the conventional landline networks, for example, PBXs and central office switches, and thereby allow them to interact directly with wireless terminals. Of course, since such systems would be required to concurrently handle both wireless and wired terminals, it would appear that such a system is qualitatively different from conventional cellular telephone systems and from conventional telephone systems.
A number of manufacturers have attempted to fulfill this need. Northern Telecom, for example, has designed a system (commercially known as the "Companion" system, with a few trial systems sold in the U.S.) that allows both wired and wireless connections to a switching machine. The wireless capability is achieved by including a base station that interacts with (at most two simultaneous) wireless terminals. The base station is connected to a controller through a single twisted pair, and the controller is connected to a conventional switch through at most six analog lines. Wired terminals may be connected to the controller through twisted pairs.
As with systems offered by other suppliers, much of what happens within the "Companion" system is considered proprietary by Northern Telecom and is therefore unknown to the public. What is known, however, is that whatever tracking or polling (if any) of the wireless terminals is carried out, and whatever hand-off capabilities are present in the system, they are implemented in and by the controller. The switch does not participate in these processes. Also, the controller interfaces with the switch only through analog lines, and therefore, all of the digital features available in the switch are lost to the terminals that are connected to the controller.
Clearly, it would be beneficial to have an arrangement where no features are lost. It would be also beneficial to design a system, architecture, and approach that can be employed with adjuncts (as in the controller of the "Companion" system) and retrofitted into existing switch arrangements, allowing them to service both wired and wireless terminals i.e., wireless telephones, wireless computers, wireless fax machines, etc. It would be even more advantageous if such a system could be incorporated into the switch itself (obviating the need for an adjunct) and yet be able to handle both wired and wireless terminals.